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The long-term variability of the Indian monsoon in the Bay of Bengal remains inconclusive due to the lack of proximal sedimentary records. To further elucidate the long-term variability of the Indian monsoon, we analyzed the paleoproductivity regime over the last 2.3 Myr at the International Ocean Discovery Program (IODP) Expedition 353 Site U1445 located near the Mahanadi Basin in the northwestern Bay of Bengal. We measured the downcore concentrations and mass accumulation rates (MARs) of biogenic opal, CaCO 3 , total organic carbon (TOC), and total nitrogen over the Mid-Pleistocene Transition (MPT) to identify the links between surface water marine biogenic production and the Indian summer monsoon. TOC MARs were found to reflect both surface water marine productivity and terrestrial organic matter through the measurements of sediment C/N ratios and δ13C SOM values. Nonetheless, we identified a shift in the paleoproductivity regime from a dominance of biogenic opal deposition prior to the MPT to the dominance of CaCO 3 deposition following the MPT. The shift in biogenic marine productivity across the MPT was closely related to riverine discharge, which was primarily controlled by the intensity of the Indian monsoon. Our results, therefore, infer a decrease in riverine discharge to the Bay of Bengal across the MPT in response to a weakened Indian summer monsoon (and/or strengthened Indian winter monsoon). In addition, changes in the intensity of the Indian monsoon across the MPT were more closely linked to the global climate cooling rather than the gradual uplift of the Himalaya and Tibetan Plateau. • A shift in the paleoproductivity regime following the Mid-Pleistocene Transition • A relationship between shift in biogenic marine productivity and riverine discharge • A decrease in riverine discharge to the Bay of Bengal across the MPT • A weakened Indian summer monsoon linked to the global climate cooling [ABSTRACT FROM AUTHOR]

The repeated growth and reduction of the ice sheet have controlled the striking variation of the continental shelf environment in the Ross Sea. Particularly, glaciomarine shelf sedimentation is closely related to the ice sheet dynamics and ice shelf development since the Last Glacial Maximum (LGM). Using the four gravity (and box) cores obtained from the northern Drygalski Basin in the western Ross Sea, multi-proxies including sediment properties, geochemical proxies, carbon isotopic values of organic matter, clay mineral compositions of fine-grained sediments, and diatom assemblage were analyzed with AMS 14C dating from bulk organic matters. Based on the core description, X-radiograph observation, and results of grain size distribution, the core sediments were classified into the seven sediment facies: clast-rich muddy diamicton, clast-rich sandy diamicton, massive mud, laminated mud, bioturbated mud, massive sandy mud, and bioturbated sandy mud. The association of these sediment facies defines the four lithologic units in terms of the depositional evolution. Lithologic unit 1 represents diamicton deposited proximal to the grounding line. When the ice sheet and ice shelf retreated since the LGM, the unsorted sediment mass was deposited proximal to the grounding line. Lithologic unit 2 consists of the massive mud deposited under the sub-ice shelf condition. During the ice sheet retreat, the fine-grained particles were transported by the meltwater plume to the sub-ice shelf floor. The biogenic materials were also transported from the seasonal open marine area to the sub-ice shelf by the currents. Lithologic unit 3 was composed of sandy mud and mud with abundant dropstones that might have been deposited at the calving line. As the calving line passed the Drygalski Basin, a large amount of the coarse fractions was deposited due to ice shelf breakup. The terrestrial sediments from the Victoria Land coast were transported from the grounding line of the remained local ice sheet, when the calving line passed the north side of Drygalski Ice Tongue. Lithologic unit 4 comprises the bioturbated mud and sandy mud that were deposited under the seasonal open marine condition. The biological productivity increased significantly during the late Holocene, while the terrestrial sedimentation decreased under seasonal open marine conditions. The diatom assemblage and δ13C values of sediment organic matter indicate the mid-Holocene warm climate with more sea ice melting. Since the LGM, the paleoenvironmental change and glaciomarine depositional evolution on the northern Drygalski Basin were closely linked with the ice sheet dynamics and ice shelf activity, in addition to the climate change during the Holocene. • Glaciomarine shelf sedimentation related to the movement of the ice sheet and ice shelf • Seven sediment facies of four gravity cores in the northern Drygalski Basin • Four lithologic units by the depositional evolution since the Last Glacial Maximum • The mid-Holocene warm climate with more sea ice melting from the diatom assemblage [ABSTRACT FROM AUTHOR]

We investigated fossil benthic and planktonic foraminifera in sediment cores FV10-05 and FV10-06-2, off Fukuoka, southwestern Japan to evaluate the impact of the Tsushima Warm Current on coastal environments around the strait between southeastern Korea and southwestern Japan during the early to middle Holocene. A cluster analysis of benthic foraminifera in these cores established four sample clusters (A, B, C, and D), which are interpreted as indicators of relatively high energy condition due to wave/current processes. Clusters A and C, characterized by attached taxa, became dominant at ∼6.6 ka. Such faunal changes are consistent with the current-influenced sedimentation, confirming that the Tsushima Warm Current reached its present-day distribution at that time. A hiatus at ∼8–7 ka has been reported in cores from deeper water off Fukuoka, whereas our shallow core shows deposition under high energy conditions was continuous even at ∼8–7 ka near the coast off river mouth. Across the strait, the maximum landward extent of benthic foraminifera occurred in the Nakdong River delta (southeastern Korea) in ∼8–7 ka, and an outer bay fauna of benthic foraminifera with seagrass beds occurred transiently in the restricted bay of the San-in district (southwestern Japan) at that time. The evolution of the Tsushima Warm Current during the early to middle Holocene thus appears to play an important role in coastal environments not only in the strait areas between southeastern Korea and southwestern Japan, but also in the San-in district. [ABSTRACT FROM AUTHOR]

• Source to estuary surveys revealed specific pollution and dam effects on river GHGs. • Pollution effects on riverine CO 2 , CH 4 , and N 2 O vary with source size and location. • Cascade weirs boost CH 4 production, offsetting CO 2 sinks in eutrophic river-estuary. • δ13C indicates wastewater-derived GHGs and temperature-enhanced CH 4 oxidation. • Basin-specific perturbations warn generalizing eutrophic river-estuary as C sinks. Large uncertainties exist regarding the combined effects of pollution and impoundment on riverine greenhouse gas (GHG) emissions. It has also been debated whether river eutrophication can transform downstream estuaries into carbon sinks. To assess human impacts on the riverine and estuarine distributions of CO 2 , CH 4 , and N 2 O, two source-to-estuary surveys along three impounded rivers in Korea were combined with multiple samplings at five or six estuarine sites. The basin-wide surveys revealed predominant pollution effects generating localized hotspots of riverine GHGs along metropolitan areas. The localized pollution effect was pronounced in the lower Han River and estuary adjacent to Seoul, while the highest GHG levels in the upper Yeongsan traversing Gwangju were not carried over into the faraway estuary. CH 4 levels were elevated across the eutrophic middle Nakdong reaches regulated by eight cascade weirs in contrast to undersaturated CO 2 indicating enhanced phytoplankton production. The levels of all three GHGs tended to be higher in the Han estuary across seasons. Higher summer-time δ13C-CH 4 values at some Nakdong and Yeongsan estuarine sites implied that temperature-enhanced CH 4 production may have been dampened by increased CH 4 oxidation. Our results suggest that the location and magnitude of pollution sources and impoundments control basin-specific longitudinal GHG distributions and estuarine carryover effects, warning against simple generalizations of eutrophic rivers and estuaries as carbon sinks. [Display omitted] [ABSTRACT FROM AUTHOR]

The Heuksan mud belt (HMB), located in the southeastern Yellow Sea, runs parallel to the southwest coast of Korea. In this study, the distribution and relative contribution of four major clay minerals are investigated using 101 surface sediment samples collected in the course of KIOST (2001, 2010, 2011) and KIGAM (2012) cruises, as well as 33 river sediment samples (four from the Huanghe River, three from the Changjiang River, and 26 from Korean rivers) in order to clarify the provenance of fine-grained sediments in the HMB. Based on this currently largest and most robust dataset available for interpretation, the clay mineral assemblages of the fine-grained sediments in the HMB are found to be on average composed of 64.7% illite, 17.9% chlorite, 11.4% kaolinite, and 5.9% smectite. Overall, the clay mineral assemblages are similar in both the northern and the southern parts of the HMB, although smectite seems to be relatively enriched in the southern part, whereas kaolinite is slightly more dominant in the northern part. This clearly indicates that the clays are mostly derived from Korean rivers and, in the southern part of the HMB, partly also from the Huanghe River in China. The new data thus confirm and strengthen the tentative interpretation of some earlier work based on a more limited dataset. [ABSTRACT FROM AUTHOR]

• Benthic foraminifera in the NRD contain the Marine, Bay, and Opportunistic taxa. • Precipitation and resultant river discharge increased in Korean Peninsula at ∼ 4 ka. • Two small maxima of low oxygen-resistant taxon represent the fluctuated TWC. • Replacement of two species implies the enhanced East Asian winter monsoon at 4.6 ka. Fossil benthic foraminifera from five cores in the Nakdong River Delta (southeast Korea) were investigated to reveal paleoenvironmental changes across the middle/late Holocene transition, particularly focusing on ∼4 ka climatic event. Based on multi-dimensional scaling, benthic foraminifera are divided into (1) Marine taxa, (2) Bay taxa, and (3) Opportunistic taxa. Planktonic/total (benthic and planktonic) foraminiferal ratio decreased abruptly during 4.6–3.3 ka, and Nonionella stella was found commonly across ∼4 ka in core ND-01 (intermediate site among the five cores). These results imply that the ∼4 ka climatic event led to the stratification of less saline epilimnetic water underlain by more saline oxygen-poor hypolimnetic water in the Nakdong River Delta. This indicates temporal increase in precipitation in the Nakdong River drainage, which can be attributed to the intensified rainfall with the second Changma peak, associated with typhoons toward the Korean Peninsula. The small twin maxima of N. stella across ∼4 ka in core ND-01 were similar to those of the total sulfur contents in both Yeja Bay (southern Korea) and Lake Togo-ike (southwestern Japan). Such similarity in the stratigraphic patterns among the remote locations can be explained by the small-scale sea-level variations with the fluctuation of the Tsushima Warm Current, in addition to changes in precipitation. The common species of Haynesina sp. A was replaced by Elphidium somaense after ∼4.6 ka, which is likely due to the shift of passive dispersal as a result of the enhanced East Asian winter monsoon and/or the change in the westerly jet path. [ABSTRACT FROM AUTHOR]

Isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGTs) and grain size distribution were investigated in surface sediments from the western Arctic Ocean including the Chukchi Sea and the adjacent northern Bering Sea to understand their source and transportation in the Arctic region and test environmental proxies derived from the GDGT composition. Coarse sediments such as sand and silty sand are distributed in the Yukon and Mackenzie River estuaries, the northern Bering Sea near Bering Strait, and some areas of the outer shelf of the Bering Sea. In the Chukchi Sea, silt, grading from sandy to clayey silt, predominates and becomes finer northward towards the deep Arctic Ocean Isoprenoid GDGTs are abundant on the outer shelf and slope of the Chukchi Sea and the upper slope of the Bering Sea. The higher abundances are attributed to a combination of higher production of marine Archaea (Thaumarchaeota) at the shelf edge, redeposition of GDGT-carrying fine particles, and better preservation of GDGTs at sites with higher sedimentation rates. The TEX 86 - and TEX 86 L -derived temperatures are not consistent with sea surface temperatures in the study area, with unrealistically high TEX 86 - and TEX 86 L -derived temperatures in samples north of 73 °N probably biased by factors other than temperature. Branched GDGTs are abundant on the Chukchi shelf and in the Yukon and Mackenzie River estuaries. At the shelf edge of the Chukchi Sea, both branched and isoprenoid GDGTs are abundant, indicating common concentration processes such as sediment redeposition and efficient preservation at sites with high sedimentation rates. Sediments from the western Arctic Ocean north of 75 °N, the Yukon and Mackenzie River estuaries, and the Yukon River have higher cyclization ratio of branched tetraethers (CBT) than sediments from the Chukchi and Bering Seas, suggesting two different sources of branched GDGTs inferred as soil and marine bacteria. [ABSTRACT FROM AUTHOR]

We report on the faunal transition of benthic foraminifera during the middle Eocene at Site U1333 (4862 m water depth, 3,560-3,720 m paleo-water depth) of Integrated Ocean Drilling Program Expedition 320 in the eastern equatorial Pacific Ocean. During the period ~41.5—10.7 Ma, which includes carbonate accumulation event 3 (CAE-3), the benthic foraminiferal accumulation rate (BFAR) increased gradually and then it declined rapidly. In contrast, BFAR was considerably lower during ~40.7--39.4 Ma, corresponding to the middle Eocene climatic optimum (MECO), and then it increased during ~39.3--38.4 Ma, including CAE-4. Diversity (E [S2oo]) was slightly lower in the upper part of the study interval than in the lower part. The most common benthic foraminifera were Nuttallides truempyi, Oridorsalis umbonatus, and Gyroidinoides spp. in association with Globocassidulina globosa and Cibicidoides grimsdalei during the period studied. Quadrimorphina profunda occurred abundantly with N. truempyi, O. umbonatus, and G. globosa during ~39.4-- 38.4 Ma, including CAE-4, although this species was also relatively common in the lower part of the study interval. Virgulinopsis navarroanus and Fursenkoina sp. A, morphologically infaunal taxa, were common during ~38.8-38.4 Ma, corresponding to the late stage of CAE-4. Based on Q-mode cluster analysis, four sample clusters were recognized and their stratigraphic distributions were generally discriminated in the lower and upper parts of the study interval. Thus, there was only a small faunal transition in the abyssal eastern equatorial Pacific during the middle to late-middle Eocene. The faunal transition recognized in this study may be related to recovery processes following intense carbonate corrosiveness in the eastern equatorial Pacific during MECO. [ABSTRACT FROM AUTHOR]

Abstract: Sediments from three Sites (U1341, U1343 and U1345) of IODP Expedition 323, located in the Bering Sea, were analyzed for variation of biogenic opal representing surface water paleoproductivity. Initial age models of three Sites (bottom age, U1341: 4.3 Ma, U1343: 2.4 Ma, U1345: 0.5 Ma) were established onboard by biostratigraphic and paleomagnetic investigations. The initial age models were tuned by δ18O stratigraphy, which was established on shore. Biogenic opal contents of sediments were analyzed for the interval of 1.3 Ma to the present. Generally, the %biogenic opal values at Site U1341 (Bowers Ridge) were significantly higher than those at the Beringian slope sites (U1343 and U1345). Higher natural gamma radiation (NGR) counts and magnetic susceptibility (MS) at the Beringian slope sites suggested a greater contribution of lithogenic matter than at Site U1341 on Bowers Ridge. The percentages of sea-ice diatoms at the Beringian slope sites are also higher than those at Bowers Ridge Sites. This is primarily attributed to the fact that the sediments from the Beringian slope area were significantly diluted by lithogenic matter derived from the Alaskan continent, and were largely affected by sea-ice cover. The cyclicity of biogenic opal accumulation rates at Site U1341 is determined to be about 160, 40, and 30 ky, whereas that at Site U1343 is determined to be about 330, 100, 40 and 20 ky. If these had been reflecting a global climate change, the cyclicity of biogenic opal contents at all sites would be consistently the same. However, the results do not show such a consistency. Obliquity is observed at both sites of the Bowers Ridge and Beringian slope. A strong eccentricity was observed only at U1343, but no signature for eccentricity was detected at U1341. Therefore, the Milankovitch cycle with 100 ky periodicity was only observed at the Beringian slope area. The results suggest that the %biogenic opal at Site U1341 indicated a local characteristic for biogenic productivity changes. Thus, the absence of the 100 ky cycle of biogenic opal at Site U1341 seems to be due to local phenomena such as water circulation, although the changes in biogenic opal productivity at Site U1341 are attributed to summer insolation. [Copyright &y& Elsevier]

Abstract: We documented new data on the late early Oligocene benthic foraminifera and sediment geochemistry in the eastern Equatorial Pacific Ocean (EEP) from Integrated Ocean Drilling Program (Exp. 320) Site U1334 (paleo-water depth: ~3650 to ~3850m) with some published data on those from Ocean Drilling Program (Leg 199) Sites 1218 (~3850 to ~4000m) and 1219 (~4270 to ~4370m) in order to understand the response of abyssal benthic foraminifera to paleoceanographic conditions during the interval ~32–28Ma. The relative abundances of Nuttallides umbonifer were distinctly different between Sites 1218 and 1219 during 31.0 to 29.9Ma, although other major taxa (e.g., Globocassidulina subglobosa, Cibicidoides spp. and Oridorsalis umbonatus) showed no marked changes. The characteristics (e.g., Shannon–Wiener (H′)) of the benthic foraminiferal fauna are affected by the abundance of a few dominant species rather than by the change in the number of species in the EEP. Based on multi-dimensional scaling (MDS), two MDS axes were recognized: MDS axis 1 (characteristic taxa: N. umbonifer and Cibicidoides sp. A) and MDS axis 2 (characteristic taxa: G. subglobosa and Bolivina huneri). The tendency of both MDS axes (1 and 2) showed a distinct depth gradient among the three sites after 28.6Ma, whereas the tendency was different from 31.0 to 28.6Ma, especially at Site 1218. Increased abundance of N. umbonifer in the EEP after ~29Ma was similar to that in the Atlantic Ocean after the expanded distribution of this species to shallower depths was finished. The faunal change at 28.6Ma might be related to the change of deep water circulation, possibly with the influences of the Southern Component Water (SCW) and/or Northern Component Water in the South Atlantic Ocean. In contrast, the faunal change at 31.0Ma might be related to the formation of the SCW and/or meridional overturning circulation in the Southern Ocean. In particular, MDS axis 1 exhibited the opposite tendency between Sites 1218 and 1219 around the Oi-2 event, whereas the depth gradient was clearly observed among the sites around the Oi-2* event. The opposite tendency of MDS axis 1 around the Oi-2 event might be explained by the varying influences of the SCW on different depths of the EEP, especially in terms of carbonate undersaturation. The influence of the SCW on benthic foraminifera in the EEP was different among the depths of the three sites in the Oi-2 event, however, the depth gradient of the SCW influence was gradually intensified in the Oi-2* event and the 28.6–28.0Ma interval. [Copyright &y& Elsevier]

Abstract: Sinking particle fluxes during two strong El Niño events (1997/98 and 2009/10) were monitored at a station (10°30´N, 131°20´W) located in the 10°N thermocline ridge area (9°–13°N, 105°–140°W) of the northeastern equatorial Pacific. The 1997/98 El Niño event resulted in two- to fourfold higher organic carbon and biogenic silica fluxes than the non-ENSO levels. In combination, these findings suggest an increase in the productivity of surface waters. The strengthening of the North Equatorial Countercurrent, due to intensified westerlies and the resulting shoaling of the thermocline, likely induced upwelling of nutrient-enriched subsurface water and enhanced biological productivity. In contrast, the 2009/10 El Niño event was only accompanied by a substantial increase in planktonic foraminifera, with minor increases in organic carbon and biogenic silica fluxes. The distinct differences in the particle composition and the biological response of the marine ecosystem during the two El Niño events are attributed to different oceanographic and atmospheric conditions generated by two different types of El Niño: the cold-tongue (CT) type and the warm-pool (WP) type. Our results, together with the findings of a previous study of the 1982/83 strong El Niño event, suggest that enhanced biological productivity occurs in the 10°N thermocline ridge area under strong El Niño conditions. Our study also provides insight into equatorial biological dynamics under the extreme CT- and WP-type El Niño conditions. This is important because the WP-type El Niño conditions are projected to increase in frequency in the future. [Copyright &y& Elsevier]

Abstract: A time-series sediment trap was operated from July 2003 to July 2008 at a station located in the 10°N thermocline ridge of the northeastern equatorial Pacific (10°30′N, 131°20′W), with the aim of understanding variations in natural background sinking-particle flux and the influence on such fluxes of ENSO (El Niño–Southern Oscillation). Each one of weak El Niño, moderate El Niño and moderate La Niña were observed during the monitoring period. During non-ENSO periods, total mass fluxes varied from 4.1 to 36.9mgm−2 d−1, with a distinct seasonal variation, ranging from an average flux of 14.0mgm−2 d−1 in the warm season (June–November) to 25.3mgm−2 d−1 in the cold season (December–May). This seasonal fluctuation was characterized by a distinct difference in CaCO3 flux between the two seasons. The enhanced particle fluxes during the cold season are attributed to the supply of nutrient-enriched subsurface water by wind-driven vertical mixing, supported by a simultaneous reduction in sea surface temperature and enhanced trade winds. The weak El Niño event occurred in the monitoring period had no recognizable effect on particle fluxes in the study area, but the moderate El Niño event was accompanied by a significant reduction in particle fluxes to 60% of the average background value in the warm season. In contrast, particle fluxes during the moderate La Niña increased to a maximum value of 129.9mgm−2 d−1, almost three times the average background value. Organic carbon and biogenic silica fluxes were most sensitive to the El Niño and La Niña conditions. The observed variations of particle fluxes are synchronized with those of chlorophyll-a, suggesting primary productivity for the main cause of flux change. The present data indicate that marked seasonal variability in background fluxes commonly exceeds the variability associated with ENSO and post-ENSO signals, which should be taken into account when evaluating the influence of ENSO on sinking particle fluxes in the 10°N thermocline ridge area. [Copyright &y& Elsevier]

The continental margin of the Ross Sea has been consistently sensitive to the advance and retreat of the Ross Ice Sheet (RIS) between the interglacial and glacial periods. This study examines changes of the glaciomarine sedimentation on the continental slope and rise to the eastern side of Hillary Canyon in the central Ross Sea, using three gravity cores collected at increasing water depths. Besides older AMS 14C ages of bulk sediments, based on the analytical results, sediment lithology was divided into units A, B1, and B2, representing Holocene, deglacial, and glacial periods, respectively. The sedimentation rate decreased as the water depth increased, with a higher sedimentation rate in the deglacial period (unit B1) than the Holocene (unit A). Biological productivity proxies were significantly higher in glacial unit B2 than in interglacial unit A, with transitional values observed in deglacial unit B1. Biological productivity generally decreased in the Antarctic continental margin during the glacial period because of extensive sea ice coverage. The higher biogenic contents in unit B2 are primarily attributed to the increased transport of eroded and reworked shelf sediments that contained abundant biogenic components to the continental slope and rise beneath the advancing RIS. Thus, glacial sedimentation on the continental slope and rise of the central Ross Sea was generally governed by the activity of the RIS, which generated melt-water plumes and debris flows at the front of the grounding line, although the continental rise might have experienced seasonally open conditions and lateral effects due to the bottom current. • Glaciomarine sedimentation in the continental slope and rise of the Ross Sea • Higher geochemical and isotopic properties of the glacial and degalcial sediments • More supply of reworked shelf sediments by the glacial advance of Ross Ice Sheet • Role of Ross Ice Sheet on the sediment deposition in the central Ross Sea [ABSTRACT FROM AUTHOR]

Abstract: Diatom assemblages of the surface and in core sediment samples from Lake Saroma (Japan) were examined for the purpose of evaluating anthropogenic effect on the coastal environmental changes. Before the first inlet excavation, the lake''s water quality and ecology were controlled by water exchange with the Okhotsk Sea as well as lake-level variation. However, large-scale ecological modification occurred, mainly due to artificial excavation and shellfish industrial farms. A distinct record of the succession of the dominant diatom taxa was preserved in core sediments. Low-oxygen water was prevalent in the lake in 1929, before the first inlet excavation. Immediately after the first inlet excavation, the low-oxygen water in the western basin of the lake began to disappear, in a trend that became increasing transparent, which has been attributed to an increasing rate of water exchange. However, the lacustrine environment of bottom sediments resumes deterioration 20years after since the first artificial excavation: the resultant deposition of river-mouth materials into the deep basin caused eutrophication and environmental disturbance of the lake bottom. At the same time, the eutrophication of surface water became intensified with the onset of intense scallop culturing beginning in 1966. Increasing organic loads deposited onto the bottom layer in the form of excreta from the scallop nursery led to more oxygen deficiency and the elution of nitrogen and phosphorus from the sediment, which again brought about eutrophication of the surface layer. Such environmental change was reflected in a decrease of benthic diatom taxa and an increase of planktonic taxa, trends which have continued until today. Particularly, the numbers of diatom assemblage have been decreasing all over the lake during the last 10years, which suggests that Lake Saroma''s present-day deterioration and eutrophication will continue or become even worse. [Copyright &y& Elsevier]

Nd-Sr isotopes (ε Nd , 87Sr/86Sr) of detrital particles, clay mineral compositions, and δ13C of sediment organic matter (δ13C SOM) at the International Ocean Discovery Program (IODP) Expedition 353 Site U1447 in the western Andaman Sea were measured to reveal the sediment provenance changes and/or weathering intensity variations in association with the Indian monsoon intensity change. The shipboard age model based on biostratigraphic data and paleomagnetic reversals shows that IODP Site U1447 preserves late Miocene (~10 Ma) sediments. Nd/Sr isotope systematics demonstrates that the sediments originated mainly from the Myanmar region, including the Irrawaddy River, Salween River, Sittang River and Indo-Burman-Arakan Ranges without a significant change of sediment provenance since the late Miocene. Thus, temporal variations of clay mineral compositions, represented as smectite/(illite + chlorite) [S/(I + C)], indicate the long-term variations of physical/chemical weathering intensity attributable to intensity changes of Indian winter/summer monsoon. A gradual decreasing trend of S/(I + C) ratios indicates stronger physical and/or weaker chemical weathering since the late Miocene, as a result of strengthening of Indian winter monsoon (and/or weakening of Indian summer monsoon), which seems be closely related to global cooling since the late Miocene. Distinct decrease of S/(I + C) ratios occurred at ~9.2–8.5 Ma, ~3.6 Ma, ~2.4 Ma, and ~1.2 Ma, which may be attributed to the combined effect of both global cooling and Tibetan Plateau Uplift as a local response. In addition, δ13C SOM values at IODP Site U1447 were higher at ~3.5 Ma and after 1.5 Ma when S/(I + C) ratio was minima, which may imply an increase of C 4 plant in Myanmar region as a result the strong Indian winter monsoon (or weak Indian summer monsoon). • Unchanged sediment provenance at IODP Site U1447 since the late Miocene • Distinct temporal variations of clay mineral compositions since the late Miocene • Long-term variation of clay minerals by weathering intensity in the Myanmar region • Weathering intensity influenced by the Indian monsoon and global climate change [ABSTRACT FROM AUTHOR]

The past ice sheet dynamics and the timing of retreat events in the paleo-record in the Ross Sea is an issue still few understood. In order to contribute to this topic, we provide a multiproxy data from marine sediment archives (cores and box cores) collected in three sites in the Central Basin (Western Ross Sea, Antarctica). Each site recorded different environments, affected by different oceanographic conditions and sedimentary regime. This makes the three investigated sediment cores and box cores unique and useful for comparison with other studied cores collected in the same basin. The data set includes physical (paleomagnetism, grain size and petrography), chemical, micropaleontological (diatom, foraminifera and silicoflagellate assemblages) analyses and cryptotephra characterization increasing the information already reported in literature. The importance of this dataset is related to a multi-disciplinary approach in a site, the Central Basin, few investigated which represents a key area to connect the Southern Ocean and the Ross Sea., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)